Threading Stainless Steel Shafts

[Leigh]

You didn't ask for the right thing.

http://www.mcmaster.com/#threaded-pr...shafts/=m97rqp

- Leigh

[Tin Can]

Leigh, stop that!

You are linking to really cool off the shelf parts. Next I will want to build a camera. Ye gads! Stop!

McMaster does have a deep catalog. The warehouse is 10 miles from me. I order tiny amounts and I have it the next morning, faster than Amazon. Sometimes by special courier. They treat every customer as if you are an idle factory waiting for parts.

Leigh, please do not stop!

This is all very interesting.

I have enough projects...

[Leigh]

McMaster is run the way American companies used to be run, putting the customer's interests ahead of their CEO's wallet.
They've been around for something like 125 years. That attitude was the norm when they started.

Too bad more companies don't follow that model.

I get one or two orders a week from them. Great people to deal with.

- Leigh

[Curt]

You didn't ask for the right thing.

http://www.mcmaster.com/#threaded-pr...shafts/=m97rqp

- Leigh

I carefully contemplated them but the smallest diameter starts at 3/8" and I needed a shaft longer than that listed. I was very pleasant in my communications with them.

[Curt]

McMaster is run the way American companies used to be run, putting the customer's interests ahead of their CEO's wallet.
They've been around for something like 125 years. That attitude was the norm when they started.

Too bad more companies don't follow that model.

I get one or two orders a week from them. Great people to deal with.

- Leigh

One thing about them is they have never fouled up an order. You get what you ordered. Reid is excellent too. Where McMaster Carr had brass gears Reid has stainless steel gears. Same with knobs, McMaster has brass and Reid had stainless steel. The two have aluminum and plastic somewhat in common. Prices between them is a factor. Reid isn't as extensive but they carry items from companies like Kipp. Between the two and some others it makes project builds easier. Stores like Lowes and Home Depot are home improvement centers not hardware stores in the old sense. Lowes dropped taps and dies in order to put in more house brand tools. Kobalt, kome on now really. Home Depot only carries taps and taps and dies packaged in fours. Very limited at that. Four dies and a handle. A fellow at lowes told me he shops at Ace. I went there and they carry just a few taps and dies. They were out of 1/4 20 and didn't know when they'd be in. Sound familiar? I'll be shopping at Tacoma Screw and Stellar industrial here locally as a secondary means. Metals by mail works great. I could drive the 30 miles down and 30 miles back but online is easier.

[Erik Larsen]

Hi Curt,

Another option I have used is to get a smooth shaft of the correct diameter for your gears and then weld on a small section of all thread on each end for the knobs. I didn't use stainless but rather regular old hot rolled from tru value hardware. Just a little tack from the mig and a little grinding and it works like a charm.
Erik

[Scott Walker]

Stainless steel is a wonderfully metal to work with but it does take a bit of experimentation to get perfect results when doing any machining. Having a good understanding of the properties of the metal is paramount as well. My area of expertise is with 316LVM, 316, and 304. Probably the most universally important aspect of machining these alloys is a good lubricant, we used jokisch paste. We tried every available product and the jokisch paste gave us the best finished surface quality by a big margin and also the longest tool life. Chances are you will not be working with fully annealed metal and work hardened stainless is indeed a bit more difficult to cut threads in. If you are threading rod it is important to get the die started squarely, believe it or not you can actually thread a rod crooked and it is way easier to get the threads crooked than straight. The easiest way to ensure the threads start straight is to cut the rod square and taper it at the proper angle and taper it uniformly all the way around, if you have a lathe this is pretty simple, if not a drill press or even a hand drill will help, you can spin the rod in the drill and get the end fairly square and evenly tapered with a smooth or second cut mill file. We literally made miles of threads in stainless steel, some utilizing a lathe or jigs to ensure the thread was square and some entirely by hand and either way the results sucked if someone got sloppy squaring and tapering the rod before threading. I also sharpened all of our taps and dies to my own specs for cutting stainless, which helps greatly as well, but likely not necessary for your application.

[Roger Thoms]

Curt, the few times I have threaded stainless steel I purchased high speed steel taps and dies. I had no success with non high speed steel. Also Scott Walkers advice on starting the die square echoes my experience. For one project that required 4 inches of thread on 5/16" rod I had to have a friend with a Lathe help me out. I just couldn't get the die started squarely enough be hand.

Btw when are we going to see photographs of you project?

Roger

[Curt]

Stainless steel is a wonderfully metal to work with but it does take a bit of experimentation to get perfect results when doing any machining. Having a good understanding of the properties of the metal is paramount as well. My area of expertise is with 316LVM, 316, and 304. Probably the most universally important aspect of machining these alloys is a good lubricant, we used jokisch paste. We tried every available product and the jokisch paste gave us the best finished surface quality by a big margin and also the longest tool life. Chances are you will not be working with fully annealed metal and work hardened stainless is indeed a bit more difficult to cut threads in. If you are threading rod it is important to get the die started squarely, believe it or not you can actually thread a rod crooked and it is way easier to get the threads crooked than straight. The easiest way to ensure the threads start straight is to cut the rod square and taper it at the proper angle and taper it uniformly all the way around, if you have a lathe this is pretty simple, if not a drill press or even a hand drill will help, you can spin the rod in the drill and get the end fairly square and evenly tapered with a smooth or second cut mill file. We literally made miles of threads in stainless steel, some utilizing a lathe or jigs to ensure the thread was square and some entirely by hand and either way the results sucked if someone got sloppy squaring and tapering the rod before threading. I also sharpened all of our taps and dies to my own specs for cutting stainless, which helps greatly as well, but likely not necessary for your application.

Scott, I spent some real time searching for the points you listed here. If I had read a description like this I would have been way ahead of the curve. I'm experienced with tap and die threading but Stainless Steel raises the bar. The lubricant is imperative and the type is important. I read about alignment and calculating formulas for finding the major and minor diameters. 60 & 90 degree angulation and other specs. In college I completed calculus, trig, and geometry but reading some descriptions caused me to go to sleep. So I beveled the end to start after I reduced the shaft diameter a little. For the real deal I'll use calipers and use more care. The threads were full depth though so I did something correct. When cutting I advanced the die only a 1/16" then backed it all the way off. Maybe overkill but it made the motion very smooth. The bottom line is cutting threads is a skill that takes practice and it is a valuable skill when learned correctly. Thanks for the instructions!

[wombat2go]

Curt
I just made a micro-focusser which connects to a pinion on a rack and is driven by a micro robotics gearmotor. Backlash had to be a minumum.
The main part was the 1/4 inch 20 tpi UNC 60 degree threaded leadscrew which I made of brass on the 1936 South Bend lathe.
The first leadscrew I made was bent, so i made another one as carefully as I could with cuts of about 4 thou inch to closely fit the nut.
It is useable but still not perfect; a very small runout in the leadscrew causes a magnified perturbation in the motion.

I think one problem is the minor diameter of that 1/4 inch thread- the material yields while the thread is being cut and next time I would use next larger diameter.
And maybe a finer pitch which is shallower.And maybe 4130 Chrom-moly which does not look so elegant but is much stronger and still quite free cutting.
You might have the same problem in threading the stainless, as 304 etc is not much higher yield than brass.
I find with ordinary all-thread, the tolerance is too loose when I use my standard taps for the internal thread.
Good Luck with your camera!